Oscillation generator



March 15, 193.8'.

Filed Nov; 2o, 1935 l D. BAsl'M,

QSCILLATION GENERATOR' /mf PEs/57mm: ,3 TEMPE/enn/,ef

CAoEFF//ENT.

Patented Mar. 15, i933 UNITED OSCILLATION GENERATOR Donald Basim,Washington, D. C., .assignon hy mesme assignments, to Bendix RadioCorpora'- tion,.New York, RLY., a corporation of Delawa. e

`Application November 20, 1935, Serial No. 50,774'

c claims. (ci. 250g-s6) This invention relates to electricalv dischargedevice oscillation generators generally. More particularly thisinvention relates to electrical discharge device oscillationgenerators'of a high frequency stabilityz An object of this invention isto provide an oscillation generator employing an electric dischargedevice adapted to generate electrical oscillations of extremely constantfrequency with- 10 out the use of any auxiliary means. t y

Another object of this invention is to provide an oscillation generatoremploying an electric discharge device adapted to generate electrical l5oscillations of extremely constant frequency over wide temperaturevariations ofthe discharge device without mechanical compensation orwithout the use of auxiliary frequency control means.

Still another object of this invention is to provide 'an electricdischarge device oscillation generator of extremely high frequencystability by employing temperature-responsive-voltagevarying means tocontrol the`potential applied to electrodes of the discharge device inaccordance with temperature variations.

Another object of this invention isto provide an electric dischargedevice oscillation generator of extremely high frequency stability inwhich electric potentials applied to selected electrodes 'of thedischarge device s :e varied in response to temperature variations.

A further object of this invention is to provide an electric dischargedevice oscillation generator of extremely high frequency stabilityemploying circuit components having substantially no tem- J peratureexpansion throughout Wide temperature ranges and employing means forcounteracting eifects ofoperating temperature variations in the electricdischarge device.

Another object of this invention is to provide an electric dischargedevice oscillation generator of relatively high frequency stabilityemploying a multiple grid electrode or a singlegrid electrode electricdischarge device employing an oscillatory circuit having a temperaturecoefficient of substantially zero and employing temperature responsivevoltage regulating means to adjust po tentia'ls applied to the electricdischarge device to compensate for the effects of temperature on thefrequency of the oscillations generated in the electric dischargedevice. Other and further objects of this invention will be apparentfrom the following specification and theclaims.

In accordancewith this invention I provide an frequency controloscillation generator adapted to generate electrical oscillations ofsubstantially constant frequency. The arrangement of my inventionemploys an electric discharge device having a cathode, an anode and'oneor more gridlike electrodes. 5 An oscillatory circuit, includinginductance and capacity elements, is connected to selected elec trodesofthe electric discharge device. Suitable sources of current supply fo-renergizing the cathode' and anode circuits are also employed. vl0

A resistor having a positive resistance-temperature coeiiicient isconnected in series with the cathode and a resistor having a positiveresistanceftemperature coeicient is connected in series with theanodecurrent supply. The values 1 5 of these resistors are adjusted togive the proper variation in potentalsapplied to the discharge deviceelectrodes throughout Wide temperature ranges.

Each, of these variations inthe potentials 2o caused by these resistors,considered separately or A individually, would effect a certainfrequency change in theoscillations generated by the oscillationgenerator. However, the eiiects of the variations 'are.such, in thecircuit arrangement 25 of my invention, as to counteract and maintainthe frequency generated substantially constant even though the electricdischarge device frequency characteristics change slightly because oftemperature changes.

Further details of this invention will be appar.- ent from the followingspecification and the drawing in which, briefly, Fig. 1 illustrates anembodiment of my invention employing the series anode excitation threeelectrode electric discharge 35 device; Fig. 2 shows an embodimentemploying the parallel anode excitation three electrode electricdischarge device; and Fig. illustrates a multiple grid electricdischarge device circuit ar. rangement embodying my invention.

Referring to Figure l in detail, reference numeral i designates athree-element electric discharge device having a cathode 2, a gridelectrode 3, and an anode d. This electric discharge device may be ofany conventional design adapt- 45 ed to generate or control theproduction of electric oscillations. The grid electrode 3 isconnectedrto the oscillatory circuit 5 which includes the inductance 6.and the variable condenser l. The inductance 6 is preferably wound withrela- 50 tively ne Wire on a form of ceramic material,

such as, isolantite or other insulating materials such as, fused quartz,boro-silicate glass and vitreous compositions having a low coemcient ofthermal expansion. The purpose of constructing 55 this' inductance. inthis manner is to produce a y unit, the physical dimensions of which donot vary appreciably with normal temperature changes.` The wire orconductor of the inductance may be wound on a suitable form of vitreousor glass material and fused-into the vitreous or glass form', thusproducing an' inductance unit with substantially permanentcharacteristics. The variable condenser 'I also is constructed to havealowv 4temperature coelcient whereby the electrical capacity thereof doesnot vary appreciably with norranges of temperatures.v The inductance 8which is coupled to the inductance 6 is also wound'withmal changes intemperature. The conducting plates of the condenser 'I are made of invar4or similar allyjiavlng a low coefficient of thermal expansion'. The.oscillatory circuit, comprising the inductance 6 and the condenser 1,when adjusted to a. predetermined frequency, will maintain thatadjustment accurately throughout wide relatively ne. wire on a form ofmaterial, such as lsolantite.

A high frequency by-pass lcondenser 9 is cont nected between the cathode2 and the oscillatory circuit 5. Another condenser I is connectedbetween the inductance 8 and the oscillatory circuit 5.- The pointatwhich the condensers 9 and Ill are connected to the oscillatory circuitis also grounded to the metal chassis or frame which is employed tosupport the component parts of the oscillation. generator. A resistor IIhaving a positive resistance-temperature coemcient is connected acrossthe condenser 9 between the cathode-2 and theoscillatory circuit E. Thisresistor II is preferably wire wound on a suitable insulation form madeof ceramic material or the like. Another resistance unit I2 is'connectedto a point between the inductance 8 and the condenser I8 and to thepositive terminal of the source of anode currentsupply I 3. Thisresistor is also made to' have a positive resistance-temperaturecoefiicient.

The resistors Il and I2 may be wound with wire made-of nichrome,manganin, or other alloys suitable for electrical resistance units,having different temperature coelcients.

The purpose of the resistors I I and I2 is to provide automaticcompensation for frequency drift or Achangewhich occurs in the dischargedevice I due to changes in ambient temperature to which the dischargedevice is subjected during operation; It has been found that when thenormal frequency drift or change in an oscillation gencrater, such as,shown in Figure l, is in the negative direction, that is, when the`frequency decreases'as the temperature is increased, that compensationfor this frequency change can be obltained either by increasing thevoltage on the cathode or decreasing the voltage on the anode, or both.An vincrease in the ambient temperature willause the resistors Il and I2to increasein value, thus increasing the voltage on the cathode anddecreasing the voltage on the anode, causing the frequency of theoscillations generated to increase. By properly proportioning thecharacanimee oscillatory circuit 5, must be designed with extreme care,as outlined above in the description of this oscillatory circuit, forexample.

'I'he complete oscillator is enclosed in a suitable `cabinet made ofshielding materials such as aluminum and the like. Where desired, thecabinet may be made with heat insulating walls.

An oscillation generator of the parallel anode excitation type isillustrated in Figure 2. This oscillation generator employs an electricdischarge device I, an oscillatory .circuit 5. and a pair lof resistorsI I and. I2 similar to the discharge device I, oscillatory circuit 5 andresistors Il and I2 shown in Figure 1. The distinction between thisoscillation generator and that shown in Figure 1 is that the source ofcurrent supply I3 is connected in parallel with the anode-cathodecircuit of the discharge device I through a high frequency choke coil I4instead of in series with the anode-cathode circuit as shown in Figure1.

An embodiment of this invention 'employing a multiple grid dischargedevice la is shown in Figure 3. This discharge device I a. is providedwith a cathode 2, a plate Q, and grid-like electrodes 3, 3a, and 3b. Theelectrode 3 is connected to the oscillatory circuit 5 including theinductance 8 and the capacity 1.. The electrode 3a is connected to theinductance 8 and functions as the anode oi' theoscillation generator.The electrode 3b is connected to ground, that is, to the metal chassisandl cathode circuit. The plate l is' connected to the resistor I5 andto the coupling condenser I8. The other terminal of the resistor I5 isconnected to the positive terminal of the source of current supply 'I3and to theresistor I2. Y The resistors II and I2y are made insubstantially the same way as the resistors II and I2 of Figs. 1 and 2.However, the resistor I5 is made to have a negativeresistance-temperature coemcient and is made of material such as carbonand the like, having negative temperature coeillcients. l

vThe purpose of the resistor I5 is to cause an increase in the voltagesupplied to the plate or coupling electrode i as the ambient temperatureincreases. This is accomplished by making the resistor I5 of materialhaving a negativetemperature coemcient such that the resistance value ofthis resistor decreases as the tentiperaturev lncreases. 'I'he eil'ectof increasing the voltage of the coupling electrode 4 is. to increasethe frequency of the oscillations generated by the discharge device Ia.

The coupling condenser I6 is provided for the purpose of coupling theoscillation generator to a Work circuit, or a circuit in which theoscillations produced are to be utilized. Oscillations of considerablepower and 4amplitude may be derived from the circuit of the generatorshown in Figure 3 without endangering the frequency stability thereof.This does not appear to be the case with oscillation generators shown inFigures 1 and 2, inasmuch as the power output of these types is ratherlimited if the high frequency sta- .bility is to be maintained. However,the generators shown in Figures 1 and 2 may be employed to advantagein-cases where low power output is desired.

The source of current supply I3, illustrated in each case as a battery,may be a suitable generator or a rectified alternating current sourcethe voltage of which is maintained substantially constant.

Suitable heater electrodes are also provided to each of the electricdischarge device cathodes as is conventional in indirectly heated typecathodes animee 1 of electric discharge devices. IThe heater may beenergized from a battery or any other convenient source oi' currentsupply.

Various modiications in the details of my invention may be made thereinwithout departing from the spirit and scope thereof and therefore I donot desire to limit this invention to the exact details described in theforegoing specication except insofar as they are deined by the claims.

What I claim and desire to secure by Letters Patent of the United Statesis as follows:

1. Anoscillation generator adapted to generate electrical oscillationsoi a high degree of frequency stability, comprising an electricdischarge 1 device having a cathode, a control electrode and an anode,an oscillatory circuit connected to said control electrode and saidcathode, an inductance for coupling said anode to said oscillatorycircuit, a source of current supply for energizing said anode,connections for connecting the negative terminal of said source ofcurrent to said oscillatory `circuit, a resistor having a positivetemperature coefilcient connected in series with said source of currentsupply and said coupling inductance for decreasing the anode energizingpotential with increase in ambient temperature and a second resistorhaving a positive temperature coemcient connected between said cathodeof said discharge device and said oscillatory circuit, for increasingthe potential of said cathode with increase in temperature said resistorbeing adapted to cooperate together to compensate for the c ects oftemperature changes on the frequency of the oscillations generated bysaid electric discharge device.

2. An oscillation generator adapted to generate electrical oscillationsof a high degree of frequency stability, comprising an electricdischarge device having a cathode, a control electrode and an anode, anoscillatory circuit having a substantially zero temperature-frequencycoetoient, con" nections between said oscillatory circuit and saidelectric discharge device, a source of current supply connected to theanode of said electric discharge device, a pair of impedance elementshaving positive temperature coefcients, connections for connecting oneof said impedance elements between said source of current supply, andsaid anode for decreasing the energizing potential applied to said anodeas the ambient temperature increases and connections for connecting theother of said impedance elements between said 'cathode and said sourceoi current supply for increasing the eectivepotential of said cathode asthe said ambient temperature increases the voltage variations in saidimpedance elements being adapted to compensate the e'ects oi ambienttemperature variations on the frequency of the oscillations generated bysaid discharge device.

3. An oscillation'generator adapted to generate electrical oscillationsof a high degree of frequency stability, comprising an electricdischarge device, means including said electric discharge deviceforgenerating electrical oscillations of a predetermined frequency andmeans connected to said electricdischarge device for varying themagnitude of selected potentials applied thereto in accordance withvariations in ambient temperature for compensating for the edects ofvariations in said ambient temperature on the frequency of theoscillations generated.

4. An oscillation generator adapted to generate electrical oscillationsof a high degree of ire-l quency stability, comprising an electricdischarge device having a cathode, a control electrode, an anode, and acoupling electrode, an oscillator; circuit having a substantially zerotemperaturefrequency coecl'ent, connections between said oscillatorycircuit and said ,electric discharge device, a source of current supplyconnected to the anode of said electric discharge devicefa.

pair of impedance elements having positive temperature coenicients.connections between said impedance elements and rsaid source of currentsupply, and an impedance element having a negative temperature coecientconnected between said source of current supply and said couplingelectrode, the voltage variations in said impedance elements beingadapted to compensate the eilects of ambient temperature variations onthe frequency of the-oscillations generated by said discharge device.

5. An oscillation generator adapted to generate electrical oscillationsof a high degree of frequency stability, comprising an electricdischarge device having a cathode, a control electrode, an anode, and acouplingelectrode, an oscillatory circuit connected to said controlelectrode and said cathode,'means for Vcoupling said anode to saidoscillatory circuit, a source of current for energizing said anode, aresistor having a positive temperature co'emcient connected in serieswith said source oi current supply and said means, a second resistorhaving a positive temperature coemcient connected in series with thecathode of said discharge device and said oscillatory circuit, and aresistor having a negative temperature coecient connected between saidcoupling electrode and said source of current, said resistors beingadapted to compensate for the effects of temperature changes on theirequency of the oscillations generated by said electric dischargedevice.

6. .en oscillation generator adapted to generate electrical oscillationsoi a high degree of frequency stability', comprising an electricdischarge device, means including said electric discharge device :forgenerating electrical oscillations of a predetermined frequency andresistance means responsive to temperature changes, connections betweensaid resistance means and said electric discharge device for varying themagnitude of selected potentials applied thereto in accordance withvariations in ambient temperature for compensating for the eectofvariations in said ambient temperature on the frequency of theoscillations generated.

DONALD BASM.

